<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title>Document</title>
    
</head>
<body>
    <div id="app"></div>
</body>
    <script src="https://unpkg.com/vue@next"></script>
    <script>
       const app = Vue.createApp({
           template: `

           <div>

            <div><input value="hello" /></div>
            <div><input v-focus value="hello" /></div>
            </div>
           `,
        })
           //自定义指令语法
           app.directive('focus',{
               mounted(el){  //当被绑定的元素挂载到DOM中时
                   el.focus();//聚焦函数
               },
           })


            const vm = app.mount("#app");
            </script>

</html>